Formula: Mn2+6V5+Si5O18(OH)
Sorosilicate (Si2O7 groups), manganese and vanadium- bearing mineral
Specific gravity: 3.65 to 3.75 measured, 3.727 calculated
Streak: Yellow-white
Colour: Brownish red
Solubility: Insoluble in water, hydrochloric and nitric acids
Common impurities: Fe,H2O

Metamorphic environments

Medaite is formed at low temperatures in veinlets cutting manganese ores (HOM).


At the type locality, the Molinello mine, Ne, Genoa, Liguria, Italy, medaite occurs as a rare associate of tiragalloite in the abandoned manganese mine. It appears as small brown grains embedded in brownish veinlets, a few millimeters thick, cutting a black manganese ore made up mainly of quartz and braunite, with traces of serpentine. In these veins, which have almost no cavities, medaite never occurs as euhedral crystals. The grains, measuring up to 1.5 mm in length but usually much smaller (0.2 to 0.4 mm) are either isolated, surrounded nearly invariably by quartz, or grouped together into aggregates measuring up to 10 mm in diameter (AM 67.85).
Associated minerals include manganese-bearing calcite, parsettensite and albite, as well as tiragalloite, braunite and quartz (HOM).

At Fianel, Ausserferrera, Ferrera, Viamala Region, Grisons, Switzerland, medaite is associated with palenzonaite, saneroite, pyrobelonite, fianelite, parsettensite, rhodochrosite, kutnohorite, aegirine and quartz (HOM).

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